Amplifier



FIG. 1 is a front view of an amplifier showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof.

The broken lines shown in the drawings illustrate portions of the amplifier that form no part of the claimed design. 

CLAIM The ornamental design for an amplifier, as shown and described. 